The package arranges that equation numbers are applied only to those equations that are referenced. This operation is similar to the showonlyrefs option of the package mathtools.
The author is Patrick Häcker. The package is Copyright © 2012-2013 Patrick Häcker.
License: lppl1.3 Version: 0.3.8, dated: 2014-04-14 Catalogued: 2014-04-14